class Person(object):
    def __init__(self,name,age):
        self.name = name
        self.age = age 
    def say_hello(self):
        print("say hello to",self.name)
    def eat(self):
        print(self.name,"is eating")
    def __str__(self) -> str:
        return "name:{}age:{}".format(self.name,self.age)
class Student(Person):
    def __init__(self, name, age,score):
        super().__init__(name, age)
        self.score =  score
    def __str__(self) -> str:
        return f"name:{self.name}age:{self.age}score:{self.score}"
    def study(self):
        print(self.name,"is studying")

add= Student("张三",18,98)
add.study()
print(add)

